This happens to me if I close CCT, and open it up again before letting it finish writing to the xml file. If you just keep refreshing the folder your profile is in, and checking the size of the xm file, once it stops growing in size, you should be alright to open CCT again. This could also be caused by closing CCT, then doing a hard shutdown before it finishes writing the xml file, and things alike.
I suggest making periodic backups just to ensure this doesn't happen again.
If you open your xml file, look for the unclosed tags. You probably did lose some times, though. If you understand how to edit xml (it isn't hard, use google if need be), you can just close the tags yourself, and at least salvage what you do have. The bottom of your file will most likely be the unclosed tags.